he is expected to say the u.s. acted quickly to avoid catastrophe. libyan rebels say the action made a difference. they advanced more than 350 miles over the weekend on a march toward tripoli that include moammar gadhafi's hometown of surat. >> rebels tried this path before but were pushed back now they have the backing of a nato and says they are taking over coalition operations. >> nato will do all aspects of the resolution nothing more nothing less. >> the increased role means the handoff over control. military missions are to a large extent completed. >> i think we have prevented the large scale slaughter that was beginning to take place has taken place in some places. >> reporter: critics say it has given the administration mixed messages. >> on one hand they say gadhafi must go. >> he expects the message to go to an end game. >> gadhafi has to go and how gadhafi goes will be up to mr. gadhafi right now. >> many in congress have called for an explanation for the u.s. mission in libya and the cost. >> kristen: president obama will speak to the na